Of interest is copending commonly owned allowed application Ser. No. 08/074,583 entitled Tube Cutter by Dubinsky et al. filed Jun. 17, 1993, now U.S. Pat. No. 5,345,682.
This invention relates to tube cutters, and more particularly, to cutters including a pair of tube supporting and cutting jaws at least one of which jaws is movable and including a force applying device for forcing the jaws together in a pipe cutting mode.
Tube cutters are in wide use and may employ manually operated mechanisms and power operated mechanisms. Manually operated mechanisms of one type employ a rigid anvil with rollers forming one jaw and a manually displacable cutter blade forming the other jaw. The blade is coupled to a threaded shaft which may also included a spring for resiliently loading the shaft. The shaft is turned to provide a tube cutting load on the tube between the blade and rollers. The cutter is then manually rotated about the tube to cut the tube. The shaft is periodically turned to provide further cutting load on the tube as the tube is cut. This type of cutter is disclosed in the aforementioned copending application.
U.S. Pat. No. 5,206,996 discloses a manually operated tube cutter. This patent discloses a cutter with a pair of spring loaded handles each of which forming a jaw, one for carrying rollers and the other a cutting blade. The rollers and blade are biased toward one another by a spring. In a second embodiment, a C-shaped device is disclosed similar to the type of cutter described above. In the latter cutter a spring biases the cutter toward the rollers and supported tube.
U.S. Pat. No. 5,088,196 discloses a power operated tube cutter. In this apparatus no spring is used. In this cutter the roller holder and the cutting blade holder are mounted to a disk in straight-grooves therein for translation toward and away from each other. The disk is mounted for rotation relative to a housing. A spur gear is attached to the disk and rotatably driven by a drive source. The disk and holders in one relative orientation have aligned cutouts for receiving a pipe to be placed between the rollers and blade. The rollers' holder is locked in place with a screw. The cutter blade is radially moved toward the pipe and rollers while the holders for the rollers and blade are rotated by a worm drive mechanism. As the blade and rollers rotate the blade is also driven toward the pipe by the worm mechanism and a friction roller to effect cutting. The drive source is reversed to align the holders with the disk cutout and to remove the cut pipe. Thus the mechanism needs to be power driven in order to engage the cutter blade with the pipe and place the holders under load.
The problem with the above manual devices, as recognized by the present inventors, is that the spring is relatively weak so that the operator may adjust the cutter blade while under spring load. To make the spring relatively stiff to increase the cutting load would make the cutter more difficult to manually manipulate. These are conflicting requirements resolved in favor of employing a weaker spring than desired for providing a cutting load. Also, such manually operated devices are relatively slow and cumbersome to use.
The problem with the power operated device described above is that a clearance must be provided between the rollers, cutter blade and tube in order to insert the tube into the assembly. After assembly, the one holder for the rollers needs to be fixed in place with a screw. This itself is cumbersome to implement since the pipe must be measured first or placed in position to determine the position of the roller holder prior to fixation. Manually loosening and tightening a screw is also cumbersome to implement especially for pipes that are located in awkward and difficult to reach locations.
A further problem recognized by the present inventors is that the power operated cutter blade necessarily must be spaced initially from the pipe in order to position the pipe between the rollers and blade. Thereafter, the power mechanism is operated to cause the blade to displace further and eventually into engagement with the pipe. This is a problem where the location of the cut on the pipe is critical. Because the tool disclosed in this patent is hand held during operation, it is not easy to manually align the cutter blade with a fixed position on the pipe as the mechanism is operated at the same time.
A tube cutter according to one embodiment of the present invention for cutting a circular cylindrical tube about a given axis comprises a housing; first and second jaws defining a tube receiving axis, the jaws including means for supporting and cutting a received tube, the jaws being axially slidably secured to the housing for displacing toward and away from each other; and centering means coupled to the jaws for simultaneously moving and centering the jaws in a first translation mode for positioning the tube receiving axis substantially coaxial with the given axis. Thus in a power operated system defining the given axis, both of the tube cutting and supporting jaws are self centered without additional adjustment.
In a further embodiment, the centering means includes a stem extending into the housing in an axial direction and including first and second threads coupled to a respective corresponding different one of the jaws, the direction of the threads coupled between the first jaw and stem being opposite to the direction of the threads coupled between the second jaw and the stem, the jaws moving simultaneously in the axial direction toward or away from each other upon rotation of the stem in a second translation mode.
In a further embodiment, a tube cutter for cutting a circular cylindrical tube comprises a housing; first and second jaws including means for supporting and cutting a received tube, at least one of the jaws being axially slidably secured to the housing for displacing toward and away from the other jaw; jaw displacement means coupled to the housing and the at least one jaw for axially displacing the at least one jaw with negligible axial load until the jaws engage the received tube in an initial tube cutting position; and load inducement means coupled to the housing and jaw displacement means for providing a resilient tube cutting load on the jaws upon the engagement of the jaws with the tube in the initial cutting position. As a result, a relatively large cutting load can be provided since no load is on the cutter and rollers during initial adjustment to the cutting position.
In a further embodiment, a tube cutter for cutting a circular cylindrical tube comprises handle means; reversible drive means secured to the handle means for selectively driving a shaft in opposite directions; and tube cutter means secured to the handle means for receiving a tube to be cut and coupled to the shaft for rotatably cutting the received tube in response to rotation of the shaft, the drive means including one way clutch means coupled to the shaft and cutter means for driving the cutter means in only one of the opposite directions and permitting the cutter means to freely rotate in the other of the opposite directions with negligible resistance.
In a further embodiment, a tube cutter having manual and power operated modes wherein in the manual mode the cutter is manually rotated about a tube to be cut and in the power mode the cutter is attached to cutter drive means for rotating the cutter about the tube to be cut. The cutter comprises a housing; a pair of jaws coupled to the housing, at least one of the jaws being movable relative to the other jaw for supporting and cutting a tube therebetween; adjustment means for causing the at least one jaw to resiliently approach the other jaw in a tube cutting mode; and means secured to the housing adapted to be coupled to and driven by the drive means.
In a still further embodiment, a tube cutter comprises a housing; a pair of tube supporting and cutting jaws secured to the housing for cutting a tube supported thereby, at least one of the jaws being movable relative to the other jaw; adjustment means for causing the at least one jaw to resiliently approach the other jaw in a tube cutting mode; drive means for rotating the housing, jaws and adjustment means about a first axis; and socket means coupled to the drive means for releasably receiving a tool, the drive means for rotating the socket means about a second axis spaced from the first axis.